Flagellated and non-flagellated regions of the same cell surface (Euglena) are being assessed for unique and common membrane associated components. At least two glycoproteins are found only on the flagellar surface, and their mode of segregation and maintenance is being examined through appropriate antibody and radiolabelling experiments. Synthesis of these glycoproteins whether internal or external will be examined with externally applied labeled sugar nucleotides followed by isolation of labeled product, and by antibody localization in permealized cells or frozen thin sections. The role of glycoproteins in flagellar growth is also being defined through the use of a recently available glycoprotein synthesis inhibitor which appears to have a marked effect on flagellar regeneration.